Epileptic neurons induce augmenting synaptic depolarizations in non-epileptic neurons (buccal ganglia, Helix pomatia).
Spread of epileptic activity was studied by inducing epileptiform activity (pentylenetetrazol, PTZ) in one part of a nervous system and by analyzing responses of neurons in a non-PTZ-treated part (identified neurons, paired buccal ganglia, Helix pomatia). Paroxysmal depolarization shifts (PDS) induced time-locked depolarizations in non-epileptic neurons (latency ca. 5 s, duration ca. 1 min, amplitude < or =20 mV). Amplitudes were augmenting during several hours of epileptic activity. Depolarizations were accompanied by an increase in membrane resistance and they were blocked in 'high Mg-low Ca' solutions. It is assumed that the potentials represent a typical widespread response of non-epileptic neurons to PDS of other neurons. This response may be induced via non-specific releases of substances of the epileptically active neurons thereby activating neighboring neurons which in turn activate neurons in control ganglion.
Wiemann
M
M
Institut für Experimentelle Epilepsieforschung, Münster, Germany.
Altrup
U
U
Speckmann
E J
EJ
D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D003292:Convulsants / Q000494:pharmacology; D004594:Electrophysiology; D004827:Epilepsy / Q000139:chemically induced / Q000473:pathology*; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000502:physiology*; D006372:Helix, Snails / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010433:Pentylenetetrazole / Q000494:pharmacology; D013569:Synapses / Q000502:physiology*
D003292:Convulsants; D010433:Pentylenetetrazole